fix refrigerator() vs thaw_process() race

refrigerator() can miss a wakeup, "wait event" loop needs a proper memory
ordering.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 2 deletions

diff --git a/kernel/power/process.c b/kernel/power/process.c
index 6d566bf7085c..0eb5c420e8ed 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -47,8 +47,10 @@ void refrigerator(void)
         recalc_sigpending(); /* We sent fake signal, clean it up */
         spin_unlock_irq(&current->sighand->siglock);
 
-        while (frozen(current)) {
-                current->state = TASK_UNINTERRUPTIBLE;
+        for (;;) {
+                set_current_state(TASK_UNINTERRUPTIBLE);
+                if (!frozen(current))
+                        break;
                 schedule();
         }
         pr_debug("%s left refrigerator\n", current->comm);